1. Field of the Invention
The present invention relates to golf balls. More particularly, the present invention relates to solid golf balls having a core, a mid layer and a cover.
2. Description of the Related Art
Golf balls have numerous dimples on the surface thereof. A role of the dimples involves causing turbulent flow separation through disrupting the air flow around the golf ball during the flight. This roll is referred to as a “dimple effect”. By causing the turbulent flow separation, a separating point of air from the golf ball shifts backwards leading to the reduction of drag. The turbulent flow separation promotes the differentia between the separating points at the upper and lower sides of the golf ball, which results from the backspin, thereby enhancing the lift force that acts upon the golf ball. Excellent dimples disrupt the air flow in a more efficient manner.
In an attempt to improve the flight performance, a variety of proposals have been made with respect to the dimples. U.S. Pat. No. 5,292,132 discloses a golf ball with very densely arranged dimples. U.S. Pat. No. 4,813,677 discloses a golf ball having a dimple pattern with combined dimples having a great diameter and dimples having a small diameter. U.S. Patent Publication No. 2002-119838 discloses a golf ball with dimples of large size.
Previously, prevailing golf balls were two-piece golf balls. In recent years, so called three-piece golf balls having a core, a mid layer and a cover were developed, and have been supplied on the market. U.S. Pat. No. 6,299,551 and U.S. Pat. No. 6,213,896 disclose three-piece golf balls having a mid layer including a thermoplastic elastomer. U.S. Pat. No. 6,576,707 discloses a three-piece golf ball having a mid layer including an ionomer resin and a thermoplastic elastomer.
According to golf balls disclosed in U.S. Pat. No. 6,299,551 and U.S. Pat. No. 6,213,896, a resilience performance of the mid layer is insufficient. A flight performance correlates to the resilience performance. These golf balls are inferior in a flight performance.
According to a golf ball disclosed in U.S. Pat. No. 6,576,707, spin upon a driver shot is apt to be excessive resulting from the mid layer having high hardness. Excessive spin leads to reduction of the flight distance. The mid layer having high hardness also adversely affects a feel at impact.
Concern for golf balls to golf players is the flight performance and feel at impact. There exists room to improve a three-piece golf ball. An object of the present invention is to provide a golf ball which is excellent in a flight performance and feel at impact.